CHAPTER TEN LIQUIDS
6.
There is an electrostatic attraction between the permanent dipoles of polar molecules. The greater the
polarity, the greater the attraction among molecules.
7.
London dispersion (LD) < dipole-dipole < H-bonding < metallic bonding, covalent network, ionic.
Yes, there is considerable overlap. Consider some of the examples in Exercise 10.86. Benzene (onh LD
forces) has a higher boiling point than acetone (dipole-dipole forces). Also, there is even more overlap
between the stronger forces (metallic, covalent, and ionic).
8.
9.
As the size of the molecule increases, the strength of the London dispersion forces also increases. As the
electron cloud gets larger, it is easier for the electrons to be drawn away from the nucleus (more
polarizable).
As the strengths of interparticle forces increase, surface tension, viscosity, melting point and boiling
point increase, while the vapor pressure decreases.
10.
Dipole forces are generally weaker than hydrogen bonding. They are similar in that they arise from an
unequal sharing of electrons. We can look at hydrogen bonding as a particularity strong dipole force.
11.
a. Polarizability of an atom refers to the ease of distorting the electron cloud. It can also refer to ,
distorting the electron clouds in molecules or ions. Polarity refers to the presence of a perma dipole
moment in a molecule.
b. London dispersion forces are present in all substances. LD forces can be referred to as
accidental dipole - induced dipole forces. Dipole - dipole forces involve the attraction of
molecules with permanent dipoles for each other.
c. inter: between; intra: within; For example, in Br2 the covalent bond is an intramolecular fonx
holding the two Br-atoms together in the molecule. The much weaker London dispersion forces are
the intermolecular forces of attraction which hold different molecules of Br2 together in the liquid
phase.